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Ni-Mn-Ge magnetic shape memory alloy and preparation method thereof

A memory alloy and magnetic technology, applied in the field of Ni-Mn-Ge magnetic material and its preparation, can solve the problems of limited application, high cost, high brittleness, etc., and achieve the effect of simple and easy preparation method

Active Publication Date: 2014-04-16
HEBEI UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] The magnetic shape memory alloys that have been discovered so far mainly include Ni-Mn-Ga, Ni-Mn-Sb, Ni-Fe-Ga, etc., but the phase transition temperature of these materials is usually lower than room temperature, and / or they are brittle and easy to fracture , which limits the application of such materials in engineering technology, so people are still constantly looking for new magnetic shape memory materials with better properties
In 2006, it was reported that the composition was Ni 50 mn 25 Ge 25 It is predicted that the material may have a higher phase transition temperature, but experiments have shown that the material in the Heusler phase can only be formed on a substrate by a thin film growth method. The preparation process is complicated, the cost is high, and it is difficult to obtain large pieces. Material

Method used

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  • Ni-Mn-Ge magnetic shape memory alloy and preparation method thereof
  • Ni-Mn-Ge magnetic shape memory alloy and preparation method thereof
  • Ni-Mn-Ge magnetic shape memory alloy and preparation method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0033] The preparation composition is: a single crystal material with magnetic shape memory effect, which is heated by radio frequency with a growth parameter of 245KHz, and argon with a positive pressure of 0.01 to 1MPa is used as a protective gas, and grown in a magnetic levitation copper crucible with a heating power of 20 kilowatts ,

[0034] Its preparation method is carried out according to the following specific steps:

[0035] (1) Weigh Ni, Mn, Ge and Si with a purity of 99.9% respectively according to the molar ratio Ni:Mn:Ge:Si=52:33:12:3 in the above composition, and put the weighed materials in Put it into a copper crucible, put it into a melting furnace, and use a mechanical pump to pre-evacuate to 5×10 -1 Pa; use a molecular pump to evacuate to 5×10 -4 Pa, high-purity argon gas (purity 99.9%) is introduced to make the internal pressure of the melting furnace chamber reach 0.1MPa; Ni is obtained by arc melting 52 mn 33 Ge 12 Si 3 Polycrystalline ingot. Duri...

Embodiment 2

[0043] The preparation composition is Ni 52 mn 33 Ge 12 sn 3 The polycrystalline alloy with magnetic shape memory effect is prepared by arc melting method, with 0.1MPa positive pressure argon as the protective gas, in a water-cooled copper crucible, to prepare polycrystalline ingots, and then to obtain polycrystalline sample. Its preparation method is carried out according to the following specific steps:

[0044] (1) Weigh Ni, Mn, Ge and Sn with a purity of 99.9% respectively according to the molar ratio of each material in the above composition Ni:Mn:Ge:Sn=52:33:12:3, and put the weighed materials in Put it into a copper crucible, put it into a melting furnace, and use a mechanical pump to pre-evacuate to 5×10 -1 Pa; use a molecular pump to evacuate to 1×10 -4 Pa, high-purity argon gas is introduced to make the internal pressure of the melting chamber reach 0.1MPa; an arc is generated, and the arc head is kept at 2-5cm above the sample and swings repeatedly in a small ...

Embodiment 3

[0049] The preparation composition is: Ni 52 mn 32 Ge 15 co 1 A magnetic shape memory alloy polycrystalline with a magnetic field-driven martensitic phase transformation effect; except that the composition becomes Ni:Mn:Ge:Co=52:32:15:1, and the blowing process in step (3) The pressure of argon is 0.05MPa, and the rotational speed of the copper wheel is 25m / s, and the rest of the steps are the same as in Example 2. The above properties were measured, and the obtained magnetization curves are shown in Table 3, from which it can be seen that the phase transition driven by the magnetic field is obvious. The obtained values ​​of the martensitic phase transition temperature and Curie temperature of the sample are shown in Table 1.

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Abstract

The invention relates to a Ni-Mn-Ge magnetic shape memory alloy of which the chemical formula is NixMnyGezMa, wherein M is a main group element or transition group element; and 51<x<55, 31<y<40, 5<z<20, a<5, x+y+z+a=100, and x, y, z and a represent atomic percents. The alloy is a monocrystalline material or polycrystalline material. The main group element is In, Sn, Sb, As or Si; and the transition group element is Ti, Fe or Co. The magnetic material with magnetic shape memory effect has shape memory effect and ferromagnetic property, and appears the property of entropic change (magnetic card effect) caused by magnetic-field-driven phase change and magnetic order degree change, wherein the change value is up to S=8J / Kkg.

Description

technical field [0001] The invention relates to a magnetic shape memory alloy with ferromagnetism and two-way shape memory effect, in particular to a Ni-Mn-Ge magnetic material with controllable magnetically induced strain and magnetic field-driven phase transition and a preparation method thereof. Background technique [0002] Common shape memory alloys have a crystal structure (hereinafter referred to as the parent phase) at a relatively high temperature, and spontaneously change into another crystal structure at a relatively low temperature, generally called a martensitic phase. When cooling from a higher temperature to a lower temperature, the material transforms from the parent phase to the martensitic phase, which is called a martensitic transformation. Conversely, by heating the material from relatively low temperatures, the alloy undergoes a transformation from the martensitic phase to the parent phase, and this opposite phase transformation is called reverse martens...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C19/03C22C1/02B22D11/06C30B29/52C30B15/00C22F1/10
Inventor 罗鸿志刘国栋孟凡斌刘何燕代学芳
Owner HEBEI UNIV OF TECH
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